1. Field of the Invention
The described invention relates to the field of data storage and transmission. In particular, the invention relates to a method of providing a data segment with minimal access latency. A data segment is defined herein as a sequential data stream of finite length. The data segment includes, but is not limited to, any combination of audio and/or video data.
2. Description of Related Art
On-demand systems are employed in various settings. For example, on-demand movies are shown on cable television and on private television networks, such as those found in a hotel. The cable company and the hotel are able to provide the video to a user upon the request of the user (on-demand). On-demand systems use a back channel to provide a signal to the cable provider's or hotel's video server to begin providing the on-demand movie. The back channel may be accessed using a remote control to transmit information of the user's request to a television set or set-top box, which in turn provides a signal to the video server. Alternatively, the user may call via telephone (the back channel) to order a movie. The movie will then be broadcast for the user to view.
Near-on demand refers to a system which may not begin immediately at the request of the user. Instead, the near-on demand system repeats at intervals that are short enough to be acceptable to the user. The user no longer needs to use a back channel to indicate that he wishes to access the data segment. Instead, he just waits for the data segment to restart in order to view the data segment from the beginning.
One way of providing a data segment using a near-on-demand system is by providing the entire data segment on multiple channels, each channel offset by a fixed time interval. For example, if a data segment is two hours long, four channels (with offsets of 0, 30, 60, and 90 minutes) would adequately allow for a person to access the data segment from the beginning every 30 minutes. The user can tune in to the channel that is next to restart the data segment from the beginning. However, this method takes many channels to reduce to a reasonable amount the access latency, i.e., the maximum waiting period until the data segment is restarted. In the above example, using four channels, a person may need to wait up to 30 minutes for the data segment to restart. This amount of time may be unacceptable to many users.